The prevalence of and predictive factors for emotional morbidity (measured by the Hospital Anxiety and Depression Scale (HAD)) one year following surgery, with special focus on dispositional optimism/pessimism (measured by the Life Orientation Test (LOT-R), was examined in 165 women, newly diagnosed with breast cancer. Patients characteristics, appraisal of cancer diagnosis, beliefs about treatment efficacy, treatment decision-making participation, coping and emotional morbidity was assessed by self-rating questionnaires. Prevalence of anxiety and depression cases at time of diagnosis was 34 and 12%, respectively, and 26 and 9% after one year. Prevalence of emotional morbidity was significantly enlarged among pessimists at all assessments. Pessimism was the strongest predictor for anxiety (OR: 0.86 C.I. 95% 0.77 - 0.95) and depression (OR: 0.83, C.I. 95% 0.73 - 0.95) one year following breast cancer surgery. Optimists and pessimists differed not only in regard to coping styles, but also in regards to predictors of emotional morbidity. Optimists experiencing anxiety at time of breast cancer diagnosis had about six times higher risk of experiencing anxiety after one year, compared to optimists without preoperative anxiety. For pessimists, the more pessimistic one was about one's overall future the higher risk for developing anxiety following one year of breast cancer surgery. Pessimists, who endorse helpless/hopeless coping style when receiving a diagnosis of breast cancer, had three times greater risk for experiencing depression one year after breast cancer surgery, than pessimists who did not. Health care professionals should therefore provide intervention for pessimists, as well as for patients with high anxiety scores at time of diagnosis.